A battery pack mounted on an electric car or a hybrid car is cooled by a cooling apparatus such as a fan to suppress a temperature rise within the battery pack. A cooling medium such as air fed from the fan flows through the battery pack to achieve heat exchange with a battery module. The air heated by the battery module is then discharged from the battery pack to cool the interior of the battery pack.
The battery pack can be mounted under a seat in an in-car space, for example. In this case, a cooling structure can be employed in which air in the in-car space can be introduced into the battery pack, introduced air flow within the battery pack, and is then discharged to the in-car space.